294 The Romance of Wild ‘Flowers 
is scattered in a minute cloud and borne by the wind 
to the stigmas of neighbouring plants. Miiller is of 
opinion that the Small Nettle owes its abundance and 
wide distribution to three things: “The early period 
of the year at which it flowers, its regular cross- 
fertilisation, and the quick ripening of its fruit.” 
The Hop (Humulus lupulus) has interest for us in 
the fact that it differs so widely in habit from the 
other members of the family in being a climbing 
plant. No doubt the founder of the species was a 
short, erect-growing plant like the modern Stinging 
Nettle, for all Hops commence life with straight 
untwisted stems and so remain until they have got 
their second or third pairs of leaves; then the next 
joint begins to describe a circle in the air, the free 
end stretching out and travelling round its base with 
the sun. But it moves more rapidly than the sun, 
for the complete circle is described in about one 
hundred and twenty-eight minutes. This revolving 
of the youngest joint of the growing stem is at first 
of an exploratory character: it is secking a support. 
Having touched against some upright stick or stem, 
it begins to curl round it in a spiral direction, and so 
continues, the rough Hop-stem also twisting on its 
own axis. This close spiral coil it will be seen is a 
necessary consequence of the revolving movement of 
the younger portion of a stem, for in its revolution it 
meets with an obstacle which arrests the lower part 
of the shoot, and only permits the upper and constantly 
lengthening portion to revolve. As the support is a 
fixture, the revolving shoot is perpetually meeting 
with resistance. Darwin has given an admirable 
illustration which makes this proceeding of the tender 
